Field of the Invention
The present invention relates to an automated bobbin-exchanger device which is capable of automatically exchanging a bobbin case when an under thread is entirely released from a bobbin and consumed in accompany with a stitching operation of a sewing machine.
Description of Related Art
In an industrial sewing machine, a bobbin case attached to a rotary hook accommodates a bobbin around which an under thread is wound. During a stitching operation of a sewing machine, clothes, fabrics or leather products are sewn up with the under thread and the upper thread in turn
released from the bobbin and supplied from a sewing needle.
The bobbin accommodates the under thread, an amount of which is extremely small compared to that of the upper thread. Each time when the under thread is consumed, it becomes often necessary to take the bobbin case off from the rotary hook and exchange the bobbin with a new one full of under thread. Especially in an embroidery machine, there usually remains a limited space under the rotary hook. For this reason, a sewing operator often find it difficult to reach his or her hand for the rotary hook, thereby taking an extended time period to exchange the bobbin case so as to resultantly reduce a sewing efficiency. Efforts have been exerted to develop automated bobbin exchangers as represented by Japanese Laid-open Patent Application Nos. 8-196766, 8-280972 and 9-066181 (referred merely to as references hereinafter).
The bobbin exchangers that the above references have disclosed, have cammed grooves to guide the bobbin case between the rotary hook and a bobbin holder. The cammed grooves, however, are structurally complicated, thereby rendering the bobbin case to travel an extended distance. An air-cylinder provided to move a chuck along the cammed grooves, has to be located slantwise due to the complicated structure of the cammed grooves. This makes unavoidably to lengthen the horizontal and vertical distance so as to require an additional space.
On the contrary, there is only a limited space under the sewing table, especially under the rotary hook, thereby remaining a room to amelioration in making the bobbin exchanger into a compact and space-saving structure.
Therefore, the present invention has been made with the above drawbacks in mind, it is a main object of the invention to provide an automated bobbin exchanger device which is capable of minimizing a transfer distance that a bobbin case travels, thus enabling users to exchange the bobbin case quickly with a simplified structure, and resultantly making the bobbin exchanger into a compact and space-saving structure.